Our Commercial heating boiler choice If your considering contracting or having a commercial boiler installed in your offices or commercial building, this is what we recommend and why:The Q 25- Q60s condensing system boiler for Heating and DHW. Multiple flue options: Horizontal, Vertical, Twin and flexible flue liners available. Highest efficiency on the market: 110.9% according to RAL UZ61. 316 stainless steel heat exchanger for continous high efficiency and reliability. W...